The Missing Waveform Information in the Orthogonal Electrocardiogram (Frank Leads)

Abstract

The orthogonal electrocardiogram (Frank leads) is a reasonable compromise between the demands of practicability and diagnostic accuracy. The accuracy has been enhanced by the use of computerized multivariate statistical procedures. The work of the last two or three decades, however, has shown that these leads account for only part of the total available surface information. In this paper, the missing waveform information with respect to the Frank leads is quantitatively and systematically determined and a method of retrieval is worked out. The essence of this method rests on the empirical evidence obtained by testing each of the 126 surface electrocardiograms for the XYZ content. The results are analyzed by a least squares, best fit procedure. The poorly fitted curves are considered as additional waveform sources. The number and the sites of the additional information are determined on a test group of 207 patients. The "total" surface waveform information is found to be represented by nine surface leads. This set of waveforms is then tested on a control group consisting of 205 patients. An average resynthesis coefficient of 96% is reached. No further resynthesis is looked for because of the estimated noise level. Although the waveforms recorded at these sites represent the minimum number of unique building blocks capable of synthesizing any waveform on the body surface, they cannot predict the surface potential distribution at all surface points. This information is "total" as far as statistical procedures-performing discriminant analysis on time-functions—are concerned. This "total" waveform information consists of a set of electrocardiograms recorded in each individual at nine well-defined anatomical locations.